1. Field of the invention.
The present invention relates to detecting and locating destructive insects and more particularly to an electric circuit for amplifying insect generated vibrations in the articles or objects being destroyed.
As is well known, insect pests have been damaging or destroying food and other articles, such as grain, fruit and wood dwellings or other property for centuries. Such insects are usually invisible, being contained by the articles being destroyed, and must be located and identified in order to provide some means of control and/or elimination. It frequently happens, as in the case of grain destroying insects and termites, extensive damage has been done before insect damage is observed.
This invention provides a portable electrical apparatus which includes a piezoelectric transducer for detecting and amplifying insect or larva produced vibrations and for locating the position or proximity of insects destroying the articles under test.
2. Description of prior art.
Prior patents featuring vibratory sound amplification have generally related to stethoscopes in which a transducer is utilized for monitoring heart beats or the sound of blood produced in passing through heart valves or for detecting fetal heart beats.
Although electronic devices for sensing insect-induced vibrations have been constructed in the past, such devices had only limited practicability due to the need for conflicting design parameters. Such devices needed to be extremely sensitive to pick up the subtle vibrations in a structure or other article caused by insects. Yet if such sensitivity was achieved, the device also picked up a large variety of vibrations caused by other phenomena, as well as human activity. This has typically limited the usefulness of such prior art devices to laboratory-type environments or has required the probe of such devices to actually penetrate the structure or article being tested in order to reduce the noise levels, thereby damaging the structure or article.
In U.S. Pat. No. 4,008,711, an apparatus is disclosed for detecting the probable existence of cerebral aneurysms in which sound waves emanating from the patient's eyes are non-invasively monitored and converted by an electronic microphone into electrical signals which are filtered, amplified, filtered again and recorded on one channel of a magnetic tape. A heart signal, to be utilized as a computer trigger signal, is filtered and recorded on another channel of the tape. The signals are then passed through a final filter to a computer having a Fourier analysis capability. Data recorded over the patient's eyes is sampled by the computer at peak pulse pressure in the cerebral vascular system and the result of the computer analysis is displayed in the form of a spectrum on a cathode ray tube and is plotted to provide a permanent record. The displayed spectrum is considered to indicate the probable existence of an aneurysm if it includes a relatively high energy peak in the range of 200 Hz. to 800 Hz. and having an amplitude one and one-half times greater than the amplitude of any adjacent peak within 50 Hz. frequency of the high energy peak.
This invention is distinctive over such prior art by providing a piezoelectric transducer mechanically connected to a probe containing and capable of noninvasively detecting vibrations in an article being destroyed by insects. The insect destructive actions, such as an insect's bite tearing off a piece of wood cellulose, are amplified sufficiently to permit an operator to hear such vibrations through a headset. Each insect generates its own particular frequency rhythm while it feeds. This frequency pattern, in addition to being heard, may be recorded for later playback and analyzation or computer graph plotted for identifying the insect.